Slagging water-gas generator



June 20, 1939. w. LINDER SLAGGING WATER-GAS GENERATOR Filed larch 2, 1937 2 Sheets-Shut 2 Patented June 20, 19 39 UNITED STATES PATENT OFFICE SLAGGING WATER-GAS GENERATOR Willy Linder, Essen-Bredeney, Germany, assignor, by mesne assignments, to Koppers Company,v Pittsburgh, Pa., a corporation of Delaware Application March 2, 1937, Serial No. 128,569

In Germany March 4, 1936 Claims. (01. 48-78) I rent through the hot bed of coke. The coke column rests upon a grate,in most cases on a revolving grate'. The liquid slag produced during the hot blow period with a hot air-blast, again solidifies as soon as the coke column is cooled by passing cold media, such as steam, through the fuel. If the melting point of the slag is relatively low, the slag bakes together. The resulting slag lumps are always very troublesome. Since it is extremely hard to extract the slag from a stationary grate, a certain type of revolving grate has been developed, which is equipped with special crushing devices,-in order to break down larger lumps of slag, so that only small pieces of slag have to be extracted. However, in unfavorable cases, for instance when dealing with coke of a low ash melting point, the formation of larger slag lumps may be so considerable, and great difficulties will arise so that even when such special revolving grate is employed it will be impossible,

to remove the slag from the producer shaft.

For eliminating those troubles, innumerable efforts have been made; It has been proposed for instance, to introduce cooling gases during the uprun period. This method is, however, not at all satisfactory for the production of water gas. The cooling of the hot zone of the charge with additional steam is very expensive, and it is always uncertain whether the steam introduced for cooling purposes will meet just those portions of the slag, which have to be crushed before being extracted.

In order to avoid completely all those troubles caused by the formation of solid slag in the watergas producer, it has been found advantageous to withdraw the slag from the gas producer not as a solid, but in liquid condition. The slag of coal generally has a low melting point, as it contains much iron oxide in the form of silicates. When gasifying such coal, it may be possible to run the gas producer in such a way, that a separation of the slag is effected by which the ash will melt at the bottom of the producer shaft and may be" withdrawn therefrom in molten condition.

Although in a comparatively short time a satisfactory type of producer gas generator, which permits the extraction of slag in liquid state, produced during the gasification of coke, was developed, it nevertheless was not possible up till now to construct and work water-gas generators,

, from which the slag in molten state may be extracted. The main reason for this lies in the fact, that in the water-gas generator, highly endothermic reactions (formation of water-gas) also take place, which'absorb the heat from the fuel which has previously been blown-hot by an air-blast and cools it down. The liquid slags 1 formed on the surface of the fuel, and likewise the slag sump collecting at the bottom of the water-gas generator, may be solidified or at least the slag in the sump may become so viscous, that it does not flow-off by itself.

The present invention. comprises a water-gas generator from which the slag may be separated in liquidcondition, and has its aim to provide for firstof all separate inlet and outlet openings for the introduction of a hot blast and for the withdrawal of the useful gas from the water-gas generator. Said inlet and outlet openings must be of such a distance from each other in the zones of the gas producer shaft, that the reduction intemperature caused at the water-gas outlets by the outflow of water-gas during the steaming period does not have any considerable effect upon the temperature at the hot blast inlets or at the bottom of the gas producer shaft, from which the slag is withdrawn. The mini-- cipal feature of my invention is characterised in that the hot blast inlets are arranged near the sole of the producer shaft, which is suitably inclined and provided with .the ash outlet at its lowest point, whereas the outlets for the useful water-gas are arranged in a zone of the gas producer shaft, situated above the hot-blast inlets and at such a distance from the air inlets, that the influence of the water-gas in the reduction of temperature just mentioned cannot take place. If necessary, it is also possible to arrange the outlets for the useful water-gas approximately of the same height as the air inlets. In this .case, the outlets for the useful water-gas are placed between the air inlets but arranged from one another at a comparatively large distance.

On account of this fundamental arrangement of the air delivery, an extensive reduction of the iron from the slag is avoided. This is of special importance for water-gas generators, in which the ash ,melting point can be increased considerably, d to the reduction of the iron, fixed in the iron-alumina-silicates of the slag, so that the slag does'not run-off from the sole of the gas producer. At those points, where the hot blast meets the coke, first of all CO: is formed at very high temperatures. This high temperature is utilized at the bottom of the gas producer, i. e.,

for the rapid discharge of the sl'ag.:- The primary gases, rich in carbon dioxide, are however reduced by the blowing carbon, which overlies'the region of molten slag. If the air admission inlets are arranged according to the invention near the sole of the gas producer, then the highest teme perature prevails at the sole ofthe gas producer and the oven atmosphere on the bottom is of an oxidising nature, so that nearly the whole quantity of fixed iron remains in the slag. If the necessary steps are taken, however, so that only a very small quantity of iron is reduced, it is often not necessary to add some admixtures, such as lime etc., which otherwise are very essential when making use of generators for dischargeof ash as molten slag.

If the melting point of ash in the fuel is howlime or open-hearth slag to the coke. Under certain conditions it may be advisable to add ironore or scraps of iron.

It is obvious, that ina gas producer according to the invention the liquid slag arriving at the sole of the shaft is not subjected to any cooling-down by the off-flowing water-gas during the steam run period, nor to the reducing influences which may lead to a solidification or viscosity, thus interrupting the continuous discharge of the liquid slag. On the other hand, the as producer according to the invention, if used for the production of water gas, gives the most favourable efficiency, since the steam during the run period is led in counter-current to the flow direction, of the hot blast gases, and thus led in counter-current to the temperature fall in the fuelbed. The heat in the gas producer provided during the blow period, is thus full utilized in the most eillcient way.

Furthermore, with my invention the hot useful gases after leaving the gas producer shaft are run through a heating space underneath the sole of the producer shaft, whence the hot gases serve for the heating of the sole of the producer shaft, from below upwards, by which is avoided loss of heatby radiation from the top downwards. In this way, the discharge of the liquid slag arriving at the sole of the gas producer shaft is further promoted by my invention.

Finally, an essential feature of my invention is to design the gas producer shaft in' such a way, that the liquid slag produced in the shaft is continuously removed from the generator. For this purpose, the bottom of the shaft is inclined and connected with an outlet, leading to a cooling vessel, arranged in front of the gas producer.

vThe slag leaving the gas producer is solidified in this cooling vessel.

Further objects and improvements of my present invention may be'taken from the following description, showing a'preferred embodiment of my invention.

In order that the invention may be more readily understood and carriedinto practice, reference is hereby made to the accompanying drawings, which illustrate a water gas generator according to my invention. for carrying out the above features.

Figure 1 of the drawings is a vertical section through the gas generator and Figure 2 is another vertical section through the gas producer on line 11-11 of Figure 3, and

Figure 3 is a horizontal section on line III-III of Figure 1.

The gas generators shown on the drawings is provided with a substantially cylindrical gas producer shaft I, formed by the refractory brickwork I. The fuel to be treated as well as the additions which may be employed are topcharged into the shaft I, through the opening 3,

'situated in the roof 4 of the shaft. The usual devices for the introduction of fuel, and sealing the shaft from egress of gas during charging, are coupled to the opening 3. These contrivances are well-known to those skilled in the art and have not been shown on the drawings, for simplicitys sake. In case the fuel, for instance coke, has a very high ash melting point, it is advisable to add known admixtures for fiuxing by whichthe melting point of'the ash is reduced. The lower part of the gas producer shaft i is sealed by a bottom 5. The bottom is likewise made from refractory brickwork, which is especially resistant against the attacks of molten ash. Magnesite or chromium magnesite bricks are preferably used for the manufacture of the bottom. The producer shaft i is tapered above the bottom at point 8, thus compensating for the smaller volume of the molten slag against the volume 'of coke. The bottom 5 of the gas producer is inclined at one or several sides towards the ash outlet I. If necessary, it is also possible to proamount of ash is formed at any time upon the bottom of the producer shaft which would alter the effective height of the shaft, as is the case with the ash when it is withdrawn from the shaft only at longer intervals. The gas producer according to the invention is therefore of advantage, since all procedures inside the producer shaft take place continually and uniformly.

A partition wall I 0 has been provided on the inside of the granulating vessel 9. This partition does not reachthe bottom of the vessel, from which results the fact that the two measuring compartments Ii and I 2 are interconnected at the bottom. The vessel is filled either with water or any other cooling medium. During operation,

the level of the cooling liquid in the compartment I2 is higher than in the compartment ll which is' connected to the interior of the producer shaft, which difference in levels is caused by the pressure existing in the producer shaft. The liquid ashleaving the producer, first of all enters the compartment ll,- where it meets with a water jet l3, which is sprayed from the nozzle ll into the compartment above the water level. Since the liquid ash meets with the violently whirling water jet, the ash jet is interrupted by the sudden cooling-down, thus causing a solidification of the slag in the form of finely distributed heated by the combustion of fuel. A high temash. .The ash grains, being stillhot, then fall into the cooling liquid and finally accumulate at the lowest point of the conical vessel 9, from where they are removed by means of a pump l6, driven by a motor l5, and forced into pipe line H. Moreover, it is advisable to provide the vessel 9 with such means 9', to keep the cooling liquid within the vessel in motion, by which a good granulation of the slag is obtained.

In order to avoid a reduction in temperature with a resulting solidification or increased viscosityof the slag in the ash discharge channel 1, it is advisable to lead continuously a partial stream of hot gas from the gas producer shaft through the channel I. For this reason the compartment II is connected to an opening l8, which is in communication with the chimney of the plant or with another space, where lower pressures prevail than in the gas produceritself. Consequently, a portion of hot gas is continuously or periodically driven-off through the opening l8, by which the channel I is kept warm in the desired way.

If this precaution is not sufficient for the temperature required to keep the slag liquid in the channel 1, then a suitable device can be introduced instead of the sealingbrick l9 or at another convenient place in the channel I, by which air and also a combustible gas, if necessary, may be led into the channel I. In this way, there is obtained either a combustion of the gases, for instance water gas, flowing from the gas producer through the channel 1, or an additional heating of the channel by means of combustible gases which are introduced separately.

Various openings have been provided in the shaft I for the introduction of reaction gas into the shaft or for the removal of same from the producer shaft at a suitable place. In case of a water-gas generator, these ports are preferably positioned and arranged as shown on the drawmgs.

It is well known that the water-gas generator must be blown hot intermittently, so that the fuel within the producer is heated to such a temperature as is required for the water-gas reaction. At another operating period, steam is passed through the hot generator charge, at which time the steam is more or less reacted with the carbon of the burning material with the formation of water gas, i. e. a mixture of hydrogen, carbon monoxide and carbon dioxide. The so-called hot-blowing of the gas producer charge is usually done by means of air, but it is also possible to make use of other gases, containing oxygen or also of pure oxygen alone.

Quite a number of air-blast inlet openings 20, which are arranged in the lower part of the shaft I, upon a frame la, very near to the bottom 5 in the shaft wall, serve for the introduction of the blast air into the gas generator shown on the drawings. These openings are connected to nozzles 2|, as shown in detail in Figure 3, which are equipped for water-cooling and are-designed substantially similar to'the nozzles of blast fur naces. The nozzles 2| are in connection with the main air pipeline 22, by means of a shut-off and'regulating valve 22b, through the pipelines 22a. The openings 2! are uniformly distributed around the periphery of the shaft I, so that the air is divided evenly over the whole section of the producer shaft. Since the openings 20 are very near to the bottom of the producer shaft, the lower part of the charge in the shaft is traversed by the air in particular and thereby perature of the slag is thus attained at the bottom of the producer shaft, so that the ash can flow off very well from the shaft to the outside.

A multitude of water-gas off-take openings 23 are provided above the air-blast inlet openings 20 in the wall of the producer shaft. The finished water gas is withdrawn from the gas generator through these openings. As shown in Figure 2, the openings 23 are in connection with the wall channels 24, leading to a preheating space 25. This space 25 is situated underneath the bottom 5- of the gas producer, which bottom rests on an arch 26. The gases flowing through the space .25 transfer their heat. to the bottom 5 of the gas producer, thus assisting in keeping liquid collecting inv the pockets can be withdrawn. The

useful gas roughly purified finally leaves the space 25 through the pipe branch 29, which is connected to the gas pipeline 30. The gases produced when the gas generator is blown hot, the

so-called blow gases, escape from the shaft through the opening 3i, which is arranged near the roof of the shaft. The blast gas off-take opening'3l likewise serves for the introduction of steam from steam supply means 3|, necessary for the formation of water-gas in the producer shaft.

The shaft openings 23, through which the useful gas is withdrawn, are enlarged towards the shaft. Their bottom is inclined downwards, whereas the ceiling is substantially horizontal. The side walls of the openings are suitably so constructed, that they are conical towards the shaft. -The fuel charged into the shaft cannot penetrate into the channel 24, due to the peculiar shape of the openings.

Due to the fact, that'the water-gas outlets 23 are arranged above and preferably staggered with respect to the air inlets 20, any disadvantageous influence of the temperature in the portion of the fuel bed in front of the respective air inlets at the bottom of the shaft is rendered impossible. This also results in avoiding the disadvantageous action of the water-gas in cooling down of' the ash, reaching the zone of the air inlets and the liquid slag can be driven-off continuously, without any difliculties.

The gas producer is suitably operated in such a way, that the hot blast of air is introduced from below upwards andthe gasifying steam is passed from the top/downwards through the gas producer filling. In this way, the heat of the lower temperature range in the upper part of the gas producer is likewise utilized for the preheating of :the gasifying steam.

Advantageously, the apparatus according to theinvention can also be used for the introduction of other gases together with steam into the gas producer shaft. in the shaft to certain reactions. It is for instance possible to add coke-oven gas to the steam, which together with the carbon may be These media are subjected and carbon. Latter is transformed into watergas in the presence of steam. If a water-gas is to be produced, containing more hydrogen than bons, so that the mixture of water gas and de-- composed coke oven gas possesses a high per-.

centage of hydrogen.

Thegas producer or shaft furnaces according to the invention are preferably built of a material with a high refractoriness and a high resistance against the attacks of molten slag. Such a material would be for instance magnesite or chromium magnesite bricks. These building materials have, however, a somewhat higher heat conductivity'than other refractories, but they reduce in the gas producer the dangerous discharge of heat from the gas producer shaft, especially from the zones adjacent to the bottom, which is attained by the new manner of heating the shaft bottom, so that the use ofsuch materials is' rendered possible, without causing any difliculties.

I have now described my present invention on the lines of a preferred embodiment thereof, but

my invention is not limited in all its aspects to 'the mode of carrying it out as describedand shown, since the invention may be variously embodied within the scope of the following claims.

I claim: 1. A slagging water-gas generator designed for alternate air blows and water-gas steam runs with separation of the ash from the bottom of the generator inliquid form comprising a fuel 'chamber having a sole adaptedvfor liquid slag provided with liquid slag outlet means, means for admitting down run water-gas making steam and for taking oif up run air blast gas at the top of fuel chamber, means connected with the bottom of the generator fuel chamber 'for introducing air for blasting the same and withdrawing downrun water gas from the base of the chamber near the -sole for liquid slag, said latter means comprising separate lower ports for inlet of blast air and separate lower ports for oif flow of down! run water gas from the generator fuel bed, the ports for inflow of blast air being disposed around the periphery of the sole for liquid slag at approximately the level of the liquid slag outlet means therefor and the outlet ports for off-flow of down run water gas being peripherally disposed around the base of the generator just above the sole at a level above the slag outlet means therefor in spaced relation in alternation with the inlet ports for air, whereby the highest temperature prevails at the sole and the atmosphere on the bottom is of an oxidizing nature so that nearly the whole quantity of fixed iron remains in the slag.

2. A slagging. water-gas generator as claimed in claim 1, and in which the lower ports for oilflow of down-run water-gas are each enlarged towards the fuel chamber, have their bottoms downwardly inclined. th ceilings substantially horizontal and their side walls conical to prevent liquid slag from flowing through the ports.

3. A slagging water-gas generator as claimed in claim 1 and in which a liquid slag discharge channel communicably connects the liquid slag discharge means for the sole with a water cooling ash sump, and in which means are provided whereby the jet of liquid slag flowing from the sole outlet means through the channel to the sump meets with a violently whirling cooling liquid in the cooling chamber to cool and disintegrate the liquid slag into fine grains of slag before it enters the sump. I

4. A slagging generator as in claim 1 characterized by the lining constituting the sole and region of the base of the generator containing the down-run water-gas outlets being constructed of heat resistant refractory material of the gharacter of chromium magnesite and magnesite rick.

5. A slagging generator as claimed in claim 1 characterized in that the down-run water-gas outlets communicate, through brick-lined channels, with a common gas collecting and off-flow chamber therefor underneath the bottom of the sole of the generator to indirectly heat the sole from below and thus prevent cooling of the liquid slag by radiation of heat from the sole through its bottom.

. WILLY LENDER. 

